The murder of an Imperial diplomat takes Din and Ana into the heart of the Empire's Apothetik division where dissecting Leviathans has led to mental corruption that's no less deadly than the physical corruption Leviathan's spread in their wake. Their case appears to be a simple locked room mystery, except the man seems to have robbed a bank vault containing Apothetik secrets after the time of death. Ana has no trouble figuring out the murder, but untangling the vault theft leads Ana and Din deeper and deeper into the secrets of the Apothetik order responsible for the alterations of Imperial servants that keeps the Empire safe. Local politicians, diplomats, and even the Apothetiks themselves have embraced forbidden practices, all in the name of the greater good. To save everyone in the city and the Empire's pipeline of alterations, Ana must make full use of her own alteration and in the process reveal what she really is to Din.